Development of reverse ultrasonic tomographic instrumentation system for monitoring irregularities on above ground gas pipeline

Abstract

This paper presents the development of reverse ultrasonic tomographic instrumentation system to monitor irregularities on gas pipeline surface for aboveground pipe inspection in oil and gas industry. It is very crucial to detect irregularities such as crack or corrosion that may lead to pipeline ruptures which will cause fires and explosion. The developed system is based on the reverse tomographic technique as the object to be imaged is located at the outside layer of pipe, with ultrasonic sensors mounted at specific distance from the object. This researchstarted with the modelling of reverse ultrasonic sensing system that consists of ultrasonic ring design configuration, arrangement of sensors and determination of image area of ultrasonic signal for fabrication purposes. Twenty-eight ultrasonic transceiver sensors are plugged in the ultrasonic ring, where the ultrasonic ring is positioned outside the external pipe surface with a fix distance of 50 mm as modelled. The inspection is based on the detection of ultrasonic signal reflected from the surface or objects to the sensors. Based on the output signal obtained in voltage values, the distance of ultrasonic reflected to the sensor is computed. Several experiments have been carried out to evaluate thecapability of the instrumentation system in detecting irregularities on the pipe. There are seven irregularities simulated around the pipe surface. The irregularities are detected based on the output signal and are analysed based on its depth, which is ranging from 0.4 to 3.3 mm. An image of pipe profile with the irregularities existence is then reconstructed. The results indicate that the developed instrumentation system is capable to detect any irregularities at